1. Field of the Invention
The present invention relates to an image forming apparatus such as an exposure apparatus in which a lithography area in a recording medium such as a printed wiring board is exposed with a light beam modulated according to image information to form an image.
2. Description of the Related Art
In the conventional laser exposure apparatus which is used as an image forming apparatus for forming a wiring pattern in the printed wiring board, the printed wiring board which becomes a subject of image exposure is loaded on a conveying stage member, and alignment marks provided at four corners of the printed wiring board are picked up with a CCD camera at a predetermined reading position while the stage member is moved in a sub-scanning direction at a predetermined speed. Then, alignment processing is executed with respect to image information by performing coordinate transformation of a subject area of lithography in a lithography coordinate system in accordance with a position of the printed wiring board obtained by the image pickup.
At a predetermined exposure position, a laser beam is modulated on the basis of the image information and deflected in a main scanning direction by a polygon mirror. Then, exposure processing is performed on the basis of the image information in such a manner that a photosensitive coating film formed on the printed wiring board is scanned and exposed with the laser beam, namely, an image (latent image) corresponding to a wiring pattern is formed in a predetermined area (lithography area) in the printed wiring board. The printed wiring board in which the image is formed is unloaded from a stage member, and the stage member from which the printed wiring board has been removed returns (horizontally moves) to an initial position and is transferred to the next process in which the next printed wiring board is exposed (for example, see Japanese Patent Application Laid-Open (JP-A) No. 2000-338432).
However, in the laser exposure apparatus adopting the above-described method, the exposure processing is not performed to the printed wiring board while an unloaded process of unloading the exposed printed wiring board from the stage member, a returning process in which the stage member returns to the initial position, a loading process of loading the unexposed printed wiring board on the stage member, and a moving process of moving the stage member to a reading position are sequentially performed. Namely, the exposure processing with respect to the printed wiring board is intermittently performed by time set aside for the above-described processes, so that production efficiency is not good. Therefore, improvement in the production efficiency has become a problem.